Magnetic soft stops for gimbals

ABSTRACT

A gimbal arrangement includes a static structure, a gimbal supported for rotation relative to the static structure, an actuator operably connected to the gimbal and configured to rotate the gimbal relative to the static structure, and a magnetic soft stop. The magnetic soft stop is connected between the static structure and the gimbal to limit rotation of the gimbal relative to the static structure to within a predetermined range. Sensor systems and imaging methods are also described.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 62/737,057 filed Sep. 26, 2018 the disclosures of each areherein incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present disclosure relates to sensor systems, and more particularlyto magnetic soft stops for limiting rotation of gimbals in sensorsystems.

2. Description of Related Art

Camera systems, such as cameras carried by vehicles like aircraft, arecommonly used to image scenes. The camera system generally includes acamera which is mounted to a gimbal. The gimbal typically rotates suchthat the camera field of view sweeps across the scene to be imaged whilethe camera collects image data. The image data is then communicated fromthe camera to an off-gimbal device for further processing or analysis.Where the camera communicates digitally roll-flex cabling is commonlyused to connect the movable camera to static structure. Typically,mechanical hard stops are employed to limit rotation of the gimbal. Themechanical hard stop prevents the rotation of the gimbal from damagingthe cabling and/or other structures in the camera system.

One challenge to mechanical hard stops is that the contact between thegimbal and the hard stop can potentially damage the camera system, suchas from forces exerted on the camera system by acceleration and/or shockduring flight. Mechanical hard stops can also impose limitations on theimaging capability of camera systems employing more than one camera withdifferently sized fields of view.

Such conventional methods and systems have generally been consideredsatisfactory for their intended purpose. However, there is still a needin the art for improved gimbal arrangements, sensor systems, and imagingmethods. The present disclosure provides a solution for this need.

SUMMARY OF THE INVENTION

A gimbal arrangement includes a static structure, a gimbal supported forrotation relative to the static structure, an actuator operablyconnected to the gimbal and configured to rotate the gimbal relative tothe static structure, and a magnetic soft stop. The magnetic soft stopis connected between the static structure and the gimbal to limitrotation of the gimbal relative to the static structure to within apredetermined range.

In certain embodiments the magnetic soft stop can include anelectromagnet. The electromagnet can be fixed relative to the staticstructure. The electromagnet can be fixed relative to the gimbal. Themagnetic soft stop can include a permanent magnet. The permanent magnetcan be fixed relative to the static structure. The permanent magnet canbe fixed relative to the gimbal. It is contemplated that the magneticsoft stop can include a ferromagnetic body. The ferromagnetic body canbe fixed relative to the static structure or the gimbal.

In accordance with certain embodiments, there can be no mechanical hardstop arranged between the gimbal and the static structure. The magneticstop can conform in fit and form to a mechanical hard stop for a DB-110sensor system. A controller can be operably connected to the magneticsoft stop. The controller can be disposed in communication with a memoryhaving instructions recorded on the memory to activate the magnetic softstop and limit rotation of the gimbal relative to the static structureto a predetermined range. A sensor, such as an imaging sensor can befixed relative to the gimbal.

It is contemplated that the gimbal can be arranged about a roll axisrelative to the static structure. The gimbal can be arranged about apitch axis relative to the static structure. The gimbal can be a firstgimbal and the gimbal arrangement can include a second gimbal. Themagnetic soft stop can be a first magnetic soft stop and the gimbalarrangement can include a second magnetic soft stop. The second softstop can be connected between the second gimbal and the first gimbal tolimit rotation of the second gimbal relative to the first gimbal.

A sensor system includes a gimbal arrangement as described above. Asensor is fixed relative to the gimbal. A controller is operablyconnected to the magnetic soft stop and is disposed in communicationwith a memory having instructions recorded on the memory to activate themagnetic soft stop and limit rotation of the gimbal relative to thestatic structure to a predetermined range. In certain embodiments themagnetic soft stop can include an electromagnet fixed relative to one ofthe static structure and the gimbal. A permanent magnet can be fixedrelative to the other of the static structure and the gimbal. There canbe no mechanical hard stop arranged between the gimbal and the staticstructure.

An imaging method includes, at a gimbal arrangement as described above,activating the magnetic soft stop and limiting rotation of the gimbalrelative to the static structure to a predetermined range using theactivated magnetic soft stop. It is contemplated that strength ofopposition between an electromagnet fixed relative to one of the gimbaland the static structure can be increased as the gimbal rotates toward alimit of the predetermined range limit deceleration of the gimbal as thegimbal reaches the limit of the predetermined range.

These and other features of the systems and methods of the subjectdisclosure will become more readily apparent to those skilled in the artfrom the following detailed description of the preferred embodimentstaken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

So that those skilled in the art to which the subject disclosureappertains will readily understand how to make and use the devices andmethods of the subject disclosure without undue experimentation,embodiments thereof will be described in detail herein below withreference to certain figures, wherein:

FIG. 1 is side elevation view of an exemplary embodiment of a sensorsystem constructed in accordance with the present disclosure, showing agimbal arrangement of the sensor system;

FIG. 2 is a side elevation view of the sensor system of FIG. 1 with thefaring removed, schematically showing the gimbal arrangement and amagnetic soft stop;

FIG. 3 is a axial end view of the sensor system of FIG. 1 with thefaring removed, schematically showing first and second sensors carriedby a roll gimbal with the magnetic soft stop arranged to limit rotationof the roll gimbal about a roll axis;

FIGS. 4 and 5 are axial end view of the sensor system of FIG. 1 with thefaring removed, showing the gimbal in first and second positions;

FIGS. 6-13 are sectional views of the gimbal arrangement of FIG. 1,schematically showing the magnetic soft stop implemented with permanentmagnets and electromagnets;

FIG. 14 is a schematic view of the sensor system of FIG. 2,schematically showing a controller operatively connected to anelectromagnet; and

FIG. 15 is a block diagram of an imaging method, showing operations ofthe imaging method.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made to the drawings wherein like referencenumerals identify similar structural features or aspects of the subjectdisclosure. For purposes of explanation and illustration, and notlimitation, a sensor system with a gimbal arrangement having a magneticsoft stop is shown in FIG. 1 and is generally indicated by referencecharacter 100. Other embodiments of gimbal arrangements, sensor systems,and imaging methods are shown in FIGS. 2-15, as will be described. Thesystems and methods described herein can be used in intelligencesurveillance and reconnaissance (ISR) sensor systems, such as in sensorsystems having two or more sensors, though the present disclosure is notlimited to ISR systems or to sensor systems having two or more sensors.

Referring to FIG. 1, sensor system 102 is shown. Sensor system 102includes gimbal arrangement 100 and is enveloped within the interior ofa faring 104. Faring 104 includes a window 106 which provides a viewingarea for data collection from a scene 10 located outside of faring 104.In the illustrated exemplary embodiment window 106 is a first window andfaring 104 includes at least one second window, e.g., a second window108(shown in FIG. 3) and a third window 110. It is contemplated thatsensor system 102 be arranged as an ISR sensor system, such as an ISRsystem carried by an aircraft 12. Examples of suitable ISR sensorsystems include dual-band ISR sensor systems, such as DB-110 sensorsystems, available United Technologies Aerospace Systems of Charlotte,N.C.

With reference to FIG. 2, gimbal arrangement 100 is shown. Gimbalarrangement 100 includes a static structure 112, a roll gimbal 114, andpitch gimbal 116. Faring 104 (shown in FIG. 1) is fixed relative tostatic structure 112 and is supported thereby. Roll gimbal 114 isconnected to static structure 112 and is supported thereby for rotationabout a roll axis 118. Rotation of roll gimbal 114 about roll axis 118is effected by a roll resolver/drive arrangement 120, which is operablyconnected to roll gimbal 114 for rotating roll gimbal 114 about rollaxis 118. As shown in FIG. 2 a controller 122 is disposed incommunication with roll resolver/drive arrangement 120 through cabling124, through which controller 122 controls rotation of roll gimbal 114about roll axis 118.

Pitch gimbal 116 is connected to roll gimbal 114 and is supportedthereby for rotation about a pitch axis 126. Rotation of pitch gimbal116 about pitch axis 126 is effected by a pitch resolver/drivearrangement 128, which is operably connected to pitch gimbal 116 forrotating pitch gimbal 116 about pitch axis 126 and which is itselfcarried by roll gimbal 114. As also shown in FIG. 2 controller 122 isdisposed in communication with pitch resolver/drive arrangement 128through cabling 124, through which controller 122 also controls rotationof pitch gimbal 116 about pitch axis 126.

Pitch gimbal 116, and therethrough roll gimbal 114, carry a first sensor130 and a second sensor 132. Second sensor 132 is arranged on a side ofroll axis 118 opposite first sensor 130, either (or both) first sensor130 and second sensor 132 being disposed in communication withcontroller 122 for receiving data from either (or both) first sensor 130and second sensor 132. Data from first sensor 130 and second sensor 132is provided through cabling 124, which provides connectivity for digitaldata communication between the sensors and controller 122. In certainembodiments cabling 124 is roll-flex type cabling.

Controller 122 is fixed relative to static structure 112. Since cabling124 runs between movable structures, e.g., pitch resolver/drivearrangement 128, first sensor 130, and second sensor 132, it isnecessary to limit the movement of one or more of the movable structuresrelative to static structure 112. This prevents damage on cabling 124that could otherwise occur from rotation of roll gimbal 114. Limitationof movement of roll gimbal 114 is effected by a magnetic soft stop 134.As will be appreciated by those of skill in the art in view of thepresent disclosure, the disadvantages otherwise associated with havingto manage cabling 124 can be offset by the advantages provided by thequality of the data communication connection provided by cabling 124,which allows first sensor 130 and second sensor 132 to communicate imagedata with the data loss that could otherwise accompany the use of a slipring or other type of data communication interface. Although aparticular magnetic soft stop arrangement is shown, e.g., magnetic softstops connected to static structure and a fixed stop member connected toa gimbal, it is to be understood and appreciated that other arrangementsare possible within the scope of the present disclosure. For example,magnetic soft stops can be carried by the gimbal. Further, pitch gimbal14 can alternatively/additionally stopped using one or more magneticsoft stops, as suitable for an intended application.

With reference to FIG. 3, sensor system 102 is shown in an axial endview. As shown in FIG. 3 roll gimbal 114 extends about roll axis 118 andcarries first sensor 130 and second sensor 132. Static structure 112extends about roll gimbal 114 and is located radially outward of rollgimbal 114. Magnetic soft stop 134 is fixed relative to static structure112. Second sensor 132 is arranged on a side of roll axis 118 oppositefirst sensor 130 and has a second sensor field of 172. Second sensorfield of view 172 is smaller than a field of view 162 of first sensor130. In certain embodiments first sensor 130 can be a wide field of viewsensor, such as optical waveband sensor. Examples of optical wavebandsensors include cameras and telescopes. In accordance with certainembodiments second sensor 132 can be a narrow field of view sensor, suchas an infrared waveband sensor. Examples of infrared sensors includeinfrared sub-waveband imaging arrays.

Referring to FIGS. 4 and 5, sensor system 102 and gimbal arrangement 100are shown. Roll gimbal 114 has a plurality of rotational positions,e.g., a first position 136 (shown in FIG. 4) and a second position 138(shown in FIG. 5) offset about roll axis 118 by 180 degrees. Rollresolver/drive arrangement 120 is operably connected to roll gimbal 114and is configured and adapted to move roll gimbal 114 between firstposition 136 and second position 138. In first position 136 roll gimbal114 has a rotary orientation about roll axis 118 such that first sensor130 is positioned proximate to window 106 for viewing scene 10 (shown inFIG. 1) through window 106. In second position 138 roll gimbal 114 isrotated 180 degrees relative to first position 136 such that secondsensor 132 is positioned proximate to window 106 for imaging scene 10.

As will be appreciated by those of skill in the art, mechanical hardstops can be used to limit the rotation of gimbals. Mechanical hardstops have the advantage that the they can prevent movement of thegimbal from outside of the intended movement range of gimbal, e.g.,outside of predetermined movement range, such as due acceleration and/orshocks that can be experienced by an aircraft carrying a sensor systemcarrying the sensor system. For example, the hard stop can physicallyinterfere with the rotation of a gimbal beyond a certain amount ofangular rotation about the rotation axis about which the gimbal issupported, potentially preventing damage to the sensor system and/orgimbal.

While generally satisfactory for their intended purpose mechanical hardstops can potentially impose a shock on the sensor itself, such as whenthe gimbal strikes the hard stop. Mechanical hard stops also typicallyprevent use of the full range of rotation of the gimbal about therotation about the rotation axis. This can potentially limit the sensingcapability of the sensor system, such as when a sensor with a relativelywide field of view carried by the gimbal is replaced with a sensorhaving a relatively narrow field of view, the sensor with the narrowfield of view having a smaller field of regard than the sensor with thewide field of regard for a given mechanical hard stop position. To limitend of travel shock and/or allow for adjustability of end travel gimbalarrangement 100 includes magnetic soft stop 134.

Magnetic soft stop 134 includes a first magnetic body 140 and a secondmagnetic body 142. First magnetic body 140 is fixed relative to rollaxis 118 and can include, for example a permanent magnet 140 (P), aferromagnetic body 142 (F_(e)), or an electromagnet, e.g., electromagnet146. Second magnetic body 142 is similar to first magnetic body 140 withthe difference that second magnetic body 142 is movable relative to rollaxis 118, e.g., is carried by roll gimbal 114 It is contemplated thatmagnetic force F between first magnetic body 140 and second magneticbody 142 limit movement of roll gimbal 114 to prevent rotary movement ofroll gimbal 114 beyond a predetermined movement range, illustrated in anexemplary way in FIGS. 4 and 5 as about 180 degrees. As will beappreciated by those of skill in the art in view of the presentdisclosure, this can eliminate the need for a mechanical hard stop tolimit rotary movement of roll gimbal 114. In certain embodimentsmagnetic soft stop 134 can conform in fit and form to a hard stop for aDB-110 sensor system, which simplifies integration of magnetic soft stop134 in such sensor systems.

Referring now to FIGS. 6 and 7, magnetic soft stop 134 is shown. Asshown in FIG. 6 magnetic soft stop 134 can include a permanent magnet140 fixed relative to static structure 112 and a ferromagnetic member142 fixed relative to roll gimbal 114. Use of ferromagnetic member 142and permanent magnet 140 allows permanent magnet 140 to cooperate todraw roll gimbal 114 into first position 136 (shown in FIG. 4) and/orsecond position 138 (shown in FIG. 5) using an attractive force Fbetween ferromagnetic member 142 and permanent magnet 140.

As shown in FIG. 8, permanent magnet 140 can be a first permanent magnetand magnetic soft stop 134 can include a second permanent magnet 144.Second permanent magnet 144 can be fixed relative to roll gimbal 114such that, as roll gimbal 114 rotates second permanent magnet 144 intoproximity of first permanent magnet 140 magnetic force F opposesrotation of roll gimbal 114. Because the magnitude of magnetic force Fcorresponds to separation between first permanent magnet 140 and secondpermanent magnet 144, this has the effect a decelerating rotationalspeed of roll gimbal 114 as second permanent magnet 144 approaches firstpermanent magnet 140—limiting the shock exerted on roll gimbal 114 as itreaches first position 136 (shown in FIG. 4) or second position 138(shown in FIG. 5).

Referring to FIGS. 9-13, it is contemplated that magnetic soft stop 134include an electromagnet 146. As shown in FIG. 9, electromagnet 146 canbe fixed relative to static structure 112 and can cooperate withpermanent magnet 140 to selectively generate magnetic force F.Alternatively, as shown in FIG. 10 electromagnet 146 can be carried byroll gimbal 114 and permanent magnet 140 can be fixed relative to staticstructure 112. Further, electromagnet 146 can cooperate withferromagnetic member 142 with one fixed relative to static structure 112and the other fixed relative to roll gimbal 114, as shown in FIGS. 11and 12. It is also contemplated that electromagnet 146 can be a firstelectromagnet 146 and that magnetic soft stop 134 include a secondmagnetic soft stop 148, one of first electromagnet 146 and secondelectromagnet 148 being fixed to static structure 112 and the other offirst electromagnet 146 and second electromagnet 148 being fixed to rollgimbal 114. As will be appreciated by those of skill in the art in viewof the present disclosure, use of electromagnet 146 allows for selectiveengagement of magnetic soft stop 134 application of a control current tofirst electromagnetic 146 and/or second electromagnet 148.

Referring now to FIG. 14, sensor system 102 is shown according to anembodiment having electromagnet 146 and a controller 150. Controller 150includes a processor 152, a device interface 154, a user interface 156,and a memory 158. Memory 158 includes a non-transitory machine readablemedium having instructions recorded in a plurality of program modules160 that, when read by processor 152 cause controller 150 to executecertain operations, e.g., operations of an imaging method 200 (shown inFIG. 15), as will be described. In this respect, responsive to a sensorselection input 164 received at user interface 156, controller 150causes roll resolver/drive arrangement 120 to rotate roll gimbal 114about roll axis 118 and within a predetermined movement range bounded bymagnetic soft stop 134, thereby presenting one of first sensor 130(shown in FIG. 2) and second sensor 132 (shown in FIG. 2) to a window,e.g., first window 106 (shown in FIG. 1), for imaging a scene.

It is contemplated that rotating roll gimbal 114 about roll axis 118 caninclude energizing and/or de-energizing electromagnet 146 and/or secondelectromagnet 148 to selectively cause magnetic soft stop 134 to boundthe movement range of roll gimbal 114. For example, when firstelectromagnet 146 and/or second electromagnet 148 is energized, rollgimbal 114 can have a smaller movement range than when firstelectromagnet 146 and/or second electromagnet 148 is not energized.Controller 150 can be implemented with software, circuitry, or acombination of both software circuitry.

Referring to FIG. 15, an imaging method 200 is shown. Imaging method 200includes receiving, at a sensor system, e.g., sensor system 102 (shownin FIG. 1), a sensor selection, as shown with box 210. Based on thesensor selection the sensor system can rotation a gimbal, e.g., rollgimbal 114 (shown in FIG. 2) of gimbal arrangement 100 (shown in FIG.1), between a first position a second position, e.g., first position 136(shown in FIG. 4) and second position 138 (shown in FIG. 5), as shownwith box 220. In certain embodiments moving the gimbal between the firstposition and the second position can include energizing anelectromagnet, e.g., first electromagnet 146 (shown in FIG. 9) and/orsecond electromagnet 148 (shown in FIG. 13).

Using the attractive and/or the repulsive force of the magnetic elementsof the magnetic soft stop the magnetic soft stop slows rotation of thegimbal as the gimbal approaches the extreme of the movement range of thegimbal, as shown with box 240. The attractive and/or repulsive forceassociated with the magnetic soft stop can be exerted on a ferromagneticmember, e.g., ferromagnetic member 142 (shown in FIG. 6), as shown withbox 242. The attractive and/or repulsive force associated with themagnetic soft stop can be generated using a permanent magnet, e.g.,permanent magnet 140 (shown in FIG. 6), as shown with box 244. Theattractive and/or repulsive force associated with the magnetic soft stopcan be generated using a first electromagnet, e.g., first electromagnet146 (shown in FIG. 9) and/or second electromagnet 148 (shown in FIG.13), as shown with box 246.

Once the gimbal is in the first position or the second position a scenecan be imaged using the imaging sensor, as shown with box 250. It iscontemplated that moving the gimbal between the first position and thesecond position can include rotating the gimbal beyond the magnetic softstop location, such as more than 360 degrees, as shown with box 260.

The methods and systems of the present disclosure, as described aboveand shown in the drawings, provide for sensor systems with superiorproperties including relatively low shock loadings in gimbalarrangements when the gimbal reaches the extreme of the gimbal movementrange and/or the ability to rotate the gimbal move than 360 degreeswithout extension and/or damage sensor cabling connected to the gimbal.While the apparatus and methods of the subject disclosure have beenshown and described with reference to preferred embodiments, thoseskilled in the art will readily appreciate that changes and/ormodifications may be made thereto without departing from the scope ofthe subject disclosure.

What is claimed is:
 1. A gimbal arrangement, comprising: a staticstructure; a gimbal supported for rotation relative to the staticstructure; an actuator operably connected to the gimbal and configuredto rotate the gimbal relative to the static structure; and a magneticsoft stop connected between the static structure and the gimbal to limitrotation of the gimbal relative to the static structure to within apredetermined range.
 2. The gimbal arrangement as recited in claim 1,wherein the magnetic soft stop includes an electromagnet.
 3. The gimbalarrangement as recited in claim 2, wherein the electromagnet is fixedrelative to the static structure.
 4. The gimbal arrangement as recitedin claim 2, wherein the electromagnet is fixed relative to the gimbal.5. The gimbal arrangement as recited in claim 1, wherein the magneticsoft stop includes a permanent magnet.
 6. The gimbal arrangement asrecited in claim 5, wherein the permanent magnet is fixed relative tothe static structure.
 7. The gimbal arrangement as recited in claim 5,wherein the permanent magnet is fixed relative to the gimbal.
 8. Thegimbal arrangement as recited in claim 1, wherein the magnetic soft stopincludes a ferromagnetic body.
 9. The gimbal arrangement as recited inclaim 8, wherein the ferromagnetic body is fixed relative to the staticstructure.
 10. The gimbal arrangement as recited in claim 8, wherein theferromagnetic body is fixed relative to the gimbal.
 11. The gimbalarrangement as recited in claim 1, wherein there is no mechanical hardstop arranged between the gimbal and the static structure.
 12. Thegimbal arrangement as recited in claim 1, wherein the magnetic soft stopconforms in fit and form of a mechanical hard stop for a DB-110 sensorsystem.
 13. The gimbal arrangement as recited in claim 1, furthercomprising a controller operably connected to the magnetic soft stop,wherein the controller is disposed in communication with a memory havinginstructions recorded on the memory to: activate the magnetic hard stop;and limit rotation of the gimbal relative to the static structure to apredetermined range.
 14. The gimbal arrangement as recited in claim 1,further comprising a sensor fixed relative to the gimbal.
 15. The gimbalarrangement as recited in claim 1, wherein the gimbal is arranged abouta roll axis relative to the static structure.
 16. The gimbal arrangementas recited in claim 1, wherein the gimbal is arranged about a pitch axisrelative to the static structure.
 17. The gimbal arrangement as recitedin claim 1, wherein the gimbal is a first gimbal and further comprisinga second gimbal, wherein the magnet is a first magnet, and furthercomprising: a second gimbal supported for rotation relative to the firstgimbal; and a second magnet arranged between the first gimbal and thesecond gimbal, wherein the second magnetic soft stop is connectedbetween the second gimbal and the first gimbal to limit rotation of thesecond gimbal relative to the first gimbal.
 18. A sensor system,comprising: a gimbal arrangement as recited in claim 1; a sensor fixedrelative to the gimbal; and a controller operably connected to themagnetic soft stop, wherein the controller is disposed in communicationwith a memory having instructions recorded on the memory to: activatethe magnetic hard stop; and limit rotation of the gimbal relative to thestatic structure to a predetermined range.
 19. The sensor system asrecited in claim 1, wherein magnetic soft stop comprises: anelectromagnet fixed relative to one of the static structure and thegimbal; and a permanent magnet fixed relative to the other of the staticstructure and the gimbal, wherein there is no mechanical hard stoparranged between the gimbal and the static structure.
 20. An imagingmethod, comprising: at a gimbal arrangement comprising a staticstructure, a gimbal supported for rotation relative to the staticstructure, an actuator operably connected to the gimbal and configuredto rotate the gimbal relative to the static structure, and a magneticsoft stop connected between the static structure and the gimbal to limitrotation of the gimbal relative to the static structure to within apredetermined range, limiting rotation of the gimbal relative to thestatic structure to a predetermined range by communicating a magneticforce between the gimbal and the static structure.